2011-10-11

XCode 4 is incredibly slow

XCode 4 has always been incredibly slow for me. The first release, 4.0, was especially bad. But that was just a .0 version. The next release 4.1 is much better, but it has also severe drawbacks, concerning performance. Everytime I start it, and not even do much with it, my system gets incredibly slow. That is on both a C2D 2.8 GHz MBP and also on a quad-core i7 MBP. Both machines come with 4 GB of RAM, and after firing XCode up and loading a large project, still at least 500 MB of it remains free. However, speed is abysmal. I just found the tool vmmap in OS X, and it gives me this output:

So the virtual memory space that XCode takes is more than 16 GB! The actual memory taken is "only" 1.1 GB, which is still huge, but my Emacs also takes 500 MB with tons of C++, Python and LaTeX buffers open.
The question is: can the unallocated, but reserved 16 GB address space degrade the performance? I have too little knowledge of the workings of virtual memory on Intel CPUs under OS X. But this value seems incredibly huge.

Update: I have asked a question on Stackoverflow, and have gotten some useful answers. What did help was removing my build/ folder from the git. Accidentally, a colleague checked in four files in the build/ folder. This made Xcode very slow, since it was checking the git status during compilation all the time. Still, Xcode 4 is much slower than Xcode 3 after this. So I also upgraded our machines to have at least 8 GB of RAM. This was definitely much of an improvement. It seems that development machines using Xcode 4 should have 8 GB RAM minimum. The more, the better...